Pipe or bar clamps are commonly used to secure material while it is being worked upon, such as drilling, or while the pieces are joined, as by nailing, screwing or gluing. Such clamps generally consist of two opposing jaws, at least one of which is laterally adjustable with respect to the other. An interconnecting bar, pipe or other support is used to position the jaws in opposition to each other. Generally one jaw is lockably slidable along the interconnecting support, while the other jaw is adjustable by a continuous thread screw. One example of a clamp such as this is the HARGRAVE Clamp Fixtures, No. 600, manufactured by the Warren Tool Corporation of Hiram, Ohio. (HARGRAVE is a registered trademark of the Warren Tool Corporation, Hiram, Ohio).
In the past, the faces of these clamp jaws generally have been of a planar configuration. Such a configuration offers a wide range of possible uses; and renders the clamp usable with a variety of types, sizes or shapes of material. The jaws may be modified slightly to promote more efficient clamping, as for example, cutting cross-hatches in the opposing faces. The cross-hatches help the clamp to grip and secure the subject material better.
It should be appreciated that planar jaw faces are limited in use for either a single piece of material, or for two or more pieces of material, having surfaces which can be positioned so as to be substantially parallel with the jaw faces and normal to the clamping forces. Given any other positioning, the pieces of material are likely to be forced out of position by the clamp. For instance, the corners of a picture frame cannot easily be held together by a planar faced clamp. It has been necessary in the past, therefore, to create special purpose tools for such operations.
Picture frame clamps are known in the art, and generally hold all four corners of a frame squarely together. Such specialty tools are efficient, but serve only the one purpose for which they are manufactured. A picture frame clamp generally would not be useful for any operation other than framing. Because the need for clamping is widely varied, it is costly and time consuming to acquire a new tool for every clamping job.
The need therefore exists, for a clamping system having mitered jaw faces, to conform to tasks requiring other than parallel, planar clamping. Further, the need also exists for removable mitered clamp jaw faces, so as to permit the clamp to be adaptable to a wide variety of clamping situations, including the clamping of planar or mitered parts.